Classification Of Lipids MCQ - Practice Questions with Answers

TYPES OF LIPIDS - Simple Lipids

Simple Lipids: These are esters of fatty acids and are linked with various alcohols. These are of following types:

1) Fats and Oils:  

• These are esters of fatty acids and glycerol. 
• Fat is solid at room temperature.
• Glycerol is an organic compound (alcohol) with three carbons, five hydrogens, and three hydroxyl (OH) groups.
• In a fat molecule, the fatty acids are attached to each of the three carbons of the glycerol molecule with an ester bond through an oxygen atom.
• Fats are also called triacylglycerols or triglycerides because of their chemical structure.
   

• When fats are rich in unsaturated fatty acids, they are called oils.
• They are liquid at room temperature.
• If there is one double bond in the molecule, then it is known as monounsaturated fat (e.g., olive oil).
• If there is more than one double bond, then it is known as a polyunsaturated fat (e.g., canola oil).
• Triglycerides are abundant and constitute about 98 per cent of all dietary lipids.
• Oils are recommended by physicians owing to their unsaturated nature. 
• Many vitamins are fat-soluble, and fats serve as a long-term storage form of fatty acids: a source of energy. 
• They also provide insulation for the body.

2). Waxes: 

• Waxes are made up of long fatty acid chains esterified to long-chain alcohols other than glycerols. 
• Waxes are produced naturally by skin glands as a protection, to keep it lubricated, pliable, and water-proof. 
• Wax also covers hair, feathers, and wool.
• Because of the hydrophobic nature of waxes, they prevent water from sticking on the surface of leaves. 

Types of Lipids - Compound Lipids and Derived Lipids

Compound Lipids: These are formed when the simple lipids combine with another compound. These are of following types:

a) Phospholipids: These contain:
            - A platform molecule (glycerol or sphingosine)
            - One or more fatty acids

            - A phosphate group
            - An alcohol component
             - The fatty acids give the hydrophobic property while the phosphate and alcohol group give hydrophilic property.

Hence, phospholipids are amphipathic.

b) Glycolipids: These are formed when carbohydrates combine with lipids. Because of presence of sphingosine, they are also called sphingolipids.
 

Derived Lipids: 

• These substances are derived by hydrolysis from compound and simple lipids.
• Steroids: These are composed of fused hydrocarbon rings and a long hydrocarbon chain. 
• Cholesterol is the most common type of steroid. It is composed of four fused hydrocarbon rings and one end of this ring contains a hydrocarbon chain while the other end has an -OH group.
• Bile salts are modified cholesterol needed for digestion of fats.